Machinery Steels : 4140

Main Characteristic

4140 is a low alloy tool steel with high strength comprises of Chromium and molybdinum as main
content to enhance strength and quenching ability Also, it can increase surface hardness through
surface quenching. Grade 4140 is not fit for high temp application over 480c due to hardness which
significantly dropped rapidly. Moreover, tempering in the range of 230-270c is not recommended.
Since it will be fragile due to blue brittleness. Tempering should be done in the range lower.
Suggestion is 190c for 204 hours which provide best ductility enough for usage.

OutStanding Properties

   High strength
   Resistance to fatigue.
   Resistance to abrasive
   Well to forgability.
   High Toughness
   Moderate in machining
   Easy in quenching and can be done by oil.
   Hardness can be achieved up to 60 HRC
   Can do induction
   Can do nitriding , hardness surface is about 650 HV
   Resistance to carbon loss at surface in moderate level.


4140 can be applied for machinery parts which require high strength such as powertrain, steering shaft
wheel shaft , piston shaft, oil boring bit, water pump part, high presure pipe, big size gear , flange, lock tool.
Also, popular among locomotive part, machinery shaft , pressure shaft, Hydraulic shaft , gear , screw
and bolt for oil and gas industry. Moreover, it can well perform for high strength machinery part.

SCM 440
1.7225 / 42CrMo4
อบอ่อน ความแข็งไม่เกิน 229 HB
ชุบแข็ง และอบคืนตัว 55-60 HRC
Chemical Composition
ส่วนผสมทาง เคมี (%wt.)
สภาพจําหน่าย Selling Condition
สภาพหลังชุบ After Quenching
C Si Mn Cr Mo S
0.38-0.45 0.10-0.40 0.60-0.90 0.9-1.20 0.15-0.30 ≤0.035
4140 คุณสมบัติทั่วไป (General Characteristic)